My tongue has a white film on it and has big fissures. it also has painful canker sores on it. this has been going on for over a month.

Need medical evaluation: There are several possibilities or combination of possibilities for your condition. These include: candidiasis, dry mouth, allergic reactions, diabetes, Crohn's disease, and other auto immune diseases. The only way you will figure this out is to have a compete medical evaluation by your doctor. Please don't put this off.

See your PCP or DDS: Most mouth ulcers, canker sores, will clear up by themselves within a week or two. You should see your GP or dentist if the ulcer gets worse or lasts for longer than 2 weeks.